java - java中读写器的实现

Question

我试图使用通知和等待来实现读写器。但我想我被困住了。 我的顺序是这样的。 RRRRRRRRRRWWWWWWWWWW 如果 main 启动时先调用 reader，就会发生这种情况。 或者 WWWWWWWRRRRRRRRRRR。如果 main 程序首先调用 writer，就会发生这种情况。 看起来读取通知根本不起作用。编写器线程永远不会执行。

如果我在 run 方法中使 while 循环无限运行，那么它只是 RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR........。作家没有机会写作。 你能看一下这个吗？

数据类

public class Data {
    private int q ;
    private boolean isAnyOneReading;

    public Data() {
    }

    public  void readQ() {
        synchronized (this){
            isAnyOneReading = true;
            System.out.println("Read start "+q);
        }
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        synchronized (this){
            isAnyOneReading = false;
            System.out.println("Read end "+q);
            notifyAll();
        }
    }

    public synchronized void writeQ(int q) {
        System.out.println(isAnyOneReading);
        while (isAnyOneReading){
            try{
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
                System.out.println("Done");
                Thread.currentThread().interrupt();
            }
        }
        System.out.println("Write start "+q);
        this.q = q;
        try{
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
            Thread.currentThread().interrupt();
        }
        System.out.println("Write end "+q);
        notifyAll();
    }
}

读者课

public class Reader implements  Runnable {
    private Data data;
    private Thread readerThread;


    public Reader(Data data) {
        this.data = data;
        readerThread = new Thread(this, "ReaderThread");
    }


    void startThread(){
        readerThread.start();
    }

    @Override
    public void run() {
        int i = 0 ;
        while (i != 5){
            data.readQ();
            i++;
        }
    }
}

作家类

public class Writer  implements  Runnable{
    private Data data;
    private Thread writerThread;

    public Writer(Data data) {
        this.data = data;
        writerThread = new Thread(this,"WriterThread," );
    }

    void startThread(){
        writerThread.start();
    }

    @Override
    public void run() {
        int i = 0 ;
        int j = 0 ;
        while (j != 5){
            data.writeQ(i++);
           // i++;
           j++;
        }
    }
}

主类

public class ReaderWriterDemo {
    public static void main(String[] args) {
        Data data = new Data();
        Reader reader = new Reader(data);
        Writer writer = new Writer(data);

        reader.startThread();
        writer.startThread();



    }
}

Answer 1

尝试从 Data 类中删除 Thread.sleep。 并像这样在 run 方法中添加 Thread.sleep 。 (粘贴一个例子):

 @Override
public void run() {
    int i = 0;
    while (i != 5) {
        data.readQ();
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            i++;
        }
    }
}